Finite Element Analysis and Biomechanical Tests of Different Internal Fixation Devices for Treatment of Pauwels III Femoral Neck Fractures

• Main Authors: Yi-Han Chang, 張以函
• Other Authors: Leou-Chyr Lin
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/sp5ays

碩士 === 國立臺北科技大學 === 機電科技研究所 === 103 === Femoral neck fracture is one of the common orthopedic injuries, However, optimal fixation of the vertical fractures with a higher Pauwels’ angle (Pauwels III) remained an unsolved problem despite extensive biomechanical and clinical research available. Based on the past literature, this study was to design a simplified femur fixture means to replace cadaver and femur sawbone specimens. It not only could save the time of preparing specimen but also could change the density parameter of sawbone specimens. However, according to the past literature, there was not too much research focusing on comparing the biomechanical analysis of simplified femur fixture and femur sawbone. Therefore, the objective of this study was to use biomechanical testing and finite element analysis to investigate the stability and biomechanical efficiency of the femoral neck with a higher Pauwels’ angle after fixation with three parallel cancellous lag screws, as well as the dynamic hip screw system. Moreover, four different configurations (A. triangle, B. inverted triangle, C. vertical-1: two superior and one inferior, D.vertical-2: one superior and two inferior) were considered for the cancellous lag screw fixation and two bone mineral density (A. normal, B. osteoporosis ) to evaluate the biomechanical efficiency for the femoral neck fracture fixation. Finite element analysis results showed that there was a highly match between the simplified femur fixture and femur sawbone model (Max Von Mises stress is displayed in the same cancellous screw (error 0.77%)), so the simplified femur fixture would be used on the biomechanical testing in this study. Biomechanical test results showed that two superior and one inferior vertical configurations of the cancellous screw had greater compression stiffness (804.24 ± 79.58 N / mm) and failure load (2.408 ± 0.359 kN) in normal bone mineral density. In addition, DHS had greater failure load (1.359 ± 0.435 kN) in osteoporosis bone mineral density. Moreover, DHS in the failure energy of these two bone mineral density (12.54 ± 4.67 J, 6.32 ± 0.87 J) are significantly better than the implanted cancellous screw. The results of this project aimed to evaluate the biomechanical efficiency of different internal fixation devices for the treatment of Pauwels type III femoral neck fractures. When the Bone mineral density was well, femur which was implanted with two superior and one inferior vertical configurations of cancellous screw had a greater and better resistance to mechanical effects of hip load. Those who suffered from osteoporosis could have the operation of dynamic hip screw, and this could provide better biomechanical effects. Furthermore, the quantified data will also be used as reference for implant design and surgical procedure improvement.